Optical height zeroing device

ABSTRACT

A leveling device for determining the zero pressure point of an external draining system with respect to a patient is provided. The leveling device generally includes a body having a viewing element defining a field of vision, and a reference point indicator spaced apart from the viewing element and disposed within the line of vision. The viewing element and the reference point indicator define a line of sight. The device further includes a horizontal level indicator mated to the body and oriented parallel to the line of sight established by the viewing element and the reference point indicator. The horizontal level indicator is effective to indicate the horizontal alignment of the body with respect to a particular reference point viewed through the viewing element and indicated by the reference point indicator. The device can optionally include a reflector element disposed adjacent the horizontal level indicator and within the field of vision, such that the horizontal level indicator is visible through the viewing element via the reflector element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is divisional application of U.S. application Ser. No.11/081,411 now U.S. Pat. No. 7,354,431, filed on Mar. 16, 2005, andentitled “Optical Height Zeroing Device,” which is a continuation ofapplication Ser. No. 10/113,803 (now U.S. Pat. No. 6,881,210), filedMar. 29, 2002, and entitled “Optical Height Zeroing Device,” now U.S.Pat. No. 6,881,210. These references are hereby incorporated byreference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a device for controlling intracranialpressure, and in particular to a leveling device for determining thezero pressure point of an external draining system with respect to apatient.

BACKGROUND OF THE INVENTION

Cerebrospinal fluid (CSF) is a clear, colorless fluid that is primarilyproduced by the choroid plexus and surrounds the brain and spinal cord.CSF constantly circulates through the ventricular system of the brainand is ultimately absorbed into the bloodstream. CSF has three importantfunctions. First, because CSF keeps the brain and spinal cord buoyant,it acts as a protective cushion or “shock absorber” to prevent injuriesto the central nervous system. Second, CSF acts as the vehicle throughwhich nutrients are delivered to the brain, and conversely, as thevehicle through which waste products are carried away from the braintissue. Finally, by flowing between the cranium and the spine, CSF cancompensate for changes in the amount of blood found in the brain.

Hydrocephalus is a neurological condition that is caused by the abnormalaccumulation of CSF within the ventricles, or cavities, of the brain.Hydrocephalus, which affects mostly infants and young children, ariseswhen the production of CSF exceeds the absorption of CSF into thebloodstream. This is usually the result of some type of blockage in thebrain that prevents the normal flow of fluid. Such blockage can becaused by a number of factors, including, for example, geneticpredisposition, intraventricular or intracranial hemorrhage, infectionssuch as meningitis, head trauma, or the like. Blockage of the flow ofCSF consequently creates an imbalance between the amount of CSF producedby the choroid plexus and the rate at which CSF is absorbed into thebloodstream, thereby increasing pressure within the ventricles in thebrain, which causes the ventricles to enlarge.

Hydrocephalus is often treated by draining cerebrospinal fluidaccumulated in the ventricles from the brain using a hydrocephalus shuntcatheter inserted through the skull and into the ventricles. Thecatheter drains the fluid away from the brain and delivers it to anotherpart of the body, such as the peritoneum or the superior vena cava. Thecatheter may employ a flow-limiting device such as a differentialpressure valve, referred to as a shunt valve, to maintain aphysiological pressure within the ventricles.

Prior to implantation of a hydrocephalus shunt, an external drainagesystem is used to control pressure within the ventricles. Externaldrainage systems are also used to assess patient response to CSFdrainage, to evaluate the brain compliance to determine the appropriateshunt pressure setting, to treat infection, to drain blood laden CSF, tomonitor intracranial pressure (ICP), and while awaiting patientstabilization. External drainage systems typically include a supportmember, e.g., an IV pole, having a moveable drip assembly with adisposable bag adjustably fastened to the support. The flow ofcerebrospinal fluid from the patient's brain can be controlled byelevating or lowering the drip assembly to alter the resistance of thefluid pathway from the brain ventricles into the drip assembly. Thisprovides a means of controlling the pressure within the ventricles.

External drainage systems are often provided with a scale movably matedto the support member for determining and controlling the ICP of thefluid in the patient's ventricles. In order for the scale to accuratelyreflect the true ICP of the patient, a zero pressure point on the scalemust be aligned at the same height as a zero reference point on thepatient, such as a point corresponding to the position of the patient'sForamen of Monro. Because this is not a visible point, the externalauditory canal is often used as a convenient external landmark. Once thezero pressure point on the scale is determined by aligning the zeropressure point on the scale with this landmark, the drip assembly can beadjusted with respect to the zero pressure point in order to control theflow of fluid from the patient's ventricular system into the dripassembly, and thereby control ICP.

A variety of techniques for measuring and aligning the zero referencepoint on the patient with the zero pressure point on the scale areknown. Laser pointers, for example, are used by attaching the laserpointer to the scale on the EDS, or positioning it adjacent the scale.The laser is then activated, and the height of the laser is adjusteduntil the laser light aligns with a zero reference point on the patient,such as a position corresponding to the auditory canal. The zeropressure point on the scale is then marked, or alternatively the scaleis positioned to align the zero pressure point marked on the scale withthe zero reference point on the patient, for the duration of use of theexternal drainage system. The drip assembly can then be adjusted withrespect to that reference pressure point in order to increase ordecrease the ICP, and thereby increase or decrease the flow of fluidfrom the patient's brain. While such laser devices have proveneffective, it can be difficult to ensure that the laser beam ishorizontally level. Additional drawbacks of laser devices include thecosts and need to power such devices, as well as any potential risksthat may result from shining a laser beam directly at a patient.

Another prior art device that is used for determining the zero pressurepoint is a telescoping antenna with a leveling bubble. The antenna isextended from the support member to the zero reference point on thepatient, and the leveling bubble is used to horizontally position theantenna. Another similar prior art device is a large L- or T-squarewhich is held perpendicular with respect to the vertical support member,and horizontal with respect to the patient. Drawbacks of these devicesinclude the need for the patient to be relatively close to the supportmember, as well as the possible risk of injuring a patient with thedevice while positioning the device adjacent the patient's zeroreference point. Such devices can also be awkward to handle, as theyoften require one person to hold the T- or L-square, while anotherperson adjusts the height of the drainage system. Moreover, T- andL-square devices are often very large, and require sizable storagespaces.

Accordingly, there exists a need for a safe, accurate, and easy to useleveling device for determining the zero pressure point of an externaldraining system with respect to a patient.

SUMMARY OF THE INVENTION

The present invention provides a leveling device for determining thezero pressure point of an external draining system with respect to apatient. The leveling device generally includes a body having a viewingelement defining a field of vision, and a reference point indicatorspaced apart from the viewing element and disposed within the line ofvision. The viewing element and the reference point indicator define aline of sight. The device further includes a horizontal level indicatormated to the body and oriented parallel to the line of sight establishedby the viewing element and the reference point indicator. The horizontallevel indicator is effective to indicate the horizontal alignment of thebody with respect to a particular reference point viewed through theviewing element and indicated by the reference point indicator.

In one embodiment, the device includes a reflector element disposedadjacent the horizontal level indicator and within the field of thevision. The reflector element is preferably disposed at an angle withrespect to the horizontal level indicator and the viewing element, suchthat the horizontal level indicator is visible through the viewingelement via the reflector element.

The device can have a variety of configurations. In an exemplaryembodiment, the reference point indicator is formed from a rigid memberhaving a tip formed thereon for indicating the reference point, and thebody of the device is adapted to be mated to a portion of an externaldrainage system, and in particular to a scale on an external drainagesystem. In one embodiment, the body can be adapted to be adjusted inboth a horizontal direction and vertical direction with respect to thescale. The leveling device can also optionally include a viewing elementthat extends outward from the body and includes a bore extendingtherethrough. A lens can optionally be disposed within the bore of theviewing element.

In other aspects of the present invention, a method of adjusting thepressure of an external medical fluid drainage system is provided. Theexternal fluid drainage system includes a support member, a scalemovably mated to the support member, a drip assembly mated to the scale,and a catheter extending from the drip assembly to a fluid drainagepoint in a patient's cerebrospinal fluid system. The method includes thestep of providing a leveling device including a body having a viewingelement defining a field of vision, and a reference point indicatorspaced apart from and disposed within the field of vision of the viewingelement. The viewing element and reference point indicator define a lineof sight. A horizontal level indicator is mated to the body and disposedparallel to the line of sight established by the viewing element and thereference point indicator. The horizontal level indicator is effectiveto indicate the horizontal alignment of the body with respect to aparticular reference point viewed through the viewing element andindicated by the reference point indicator thereby establishing the samevertical height for the body and the particular reference point. Themethod further includes the steps of aligning the body horizontallyusing the horizontal level indicator, determining the reference point onthe patient, viewing the reference point through the viewing element,and vertically aligning the reference point indicator with the referencepoint while maintaining the horizontal alignment of the body, andthereby establishing a zero reference point. The zero reference point ispreferably the position at which the pressure differential between thepatient's cerebrospinal fluid system and the fluid drainage system iszero. In a further embodiment, the method can include the step ofadjusting the drip assembly with respect to the zero reference point tochange the pressure differential.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view illustration of a leveling device accordingto one embodiment of the present invention;

FIG. 2 is a side view schematic illustration of the components of theleveling device of FIG. 1;

FIG. 3 is an illustration of the leveling device of FIG. 1 as viewedthrough a viewing element disposed on the device;

FIG. 4 is a schematic illustration of a leveling device attached to ascale on an external drainage system, according to another embodiment ofthe present invention; and

FIG. 5 is a schematic illustration of an external drainage system havinga zero pressure point indicated on the scale, and having an adjustedICP.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a leveling device for vertically aligningtwo objects positioned at a distance apart from one another. Moreparticularly, a leveling device for use with an external drainage systemis provided. The leveling device is effective to determine and set thezero pressure point on an external draining system with respect to apatient. The zero pressure point is the point at which the ICP is zero,and thus the pressure differential between the patient's cerebrospinalfluid system and an external drainage system is zero. Once the zeropressure point is determined, the ICP can be adjusted to accuratelycontrol the flow of fluid from the patient to the external drainagesystem.

As shown in FIGS. 1 and 2, the device 10 generally includes a body 12having a viewing element 14 defining a field of vision F, and areference point indicator 16 spaced apart from the viewing element 14and disposed within the field of vision F. The viewing element 14 andthe reference point indicator 16 define a line of sight S. The device 10further includes a horizontal level indicator 18 mated to the body 12and oriented parallel to the line of sight S established by the viewingelement 14 and the reference point indicator 16. The horizontal levelindicator 18 is effective to indicate the horizontal alignment of thebody 12 with respect to a particular reference point X viewed throughthe viewing element 14 and indicated by the reference point indicator16. The device 10 can also optionally include a reflector element 20disposed adjacent the horizontal level indicator 18 and within the fieldof vision F. The reflector element 20 is disposed at an angle A withrespect to the horizontal level indicator 18 and the viewing element 14,such that the horizontal level indicator 18 is visible through theviewing element 14 via the reflector element 20.

The body 12 of the device 10, shown in FIG. 1, can have a variety ofconfigurations, but is preferably a rigid member that is configured tosupport the viewing element 14, the reference point indicator 16, thehorizontal level indicator 18, and optionally the reflector element 20.While the body 12 can have virtually any configuration, shape and size,FIG. 1 illustrates an exemplary embodiment of a body 12 having agenerally rectangular shape, and including a proximal end 22, a distalend 24, a front surface 26, and a back surface 28. The body 12 includesa length l_(b), width w_(b), and height h_(b) which can vary, butpreferably the body 12 has a length l_(b) in the range of about 40 to 80mm, a width w_(b) in the range of about 3 to 10 mm, and height h_(b) inthe range of about 30 to 100 mm.

The components 14, 16, 18, 20 of the device 10 can be mated to anyportion of the body 12, but are preferably disposed on the front surface26 of the body 12. The components 14, 16, 18, 20 can be formedintegrally with the body 12, or they can be mated to the device 10 usinga variety of attachment mechanisms including, for example, a rivet,screw, snap, buckle, adhesive, or similar attachment mechanism.

The back surface 28 of the body 12 can be a substantially flat surface,or alternatively can include a mating element (not shown) for mating thebody 12 to an external drainage system 80 as shown in FIGS. 5 and 6. Inan exemplary embodiment, the body 12 is adapted to be removably mated toa support member 86 of an external drainage system 80, and in particularto a scale 88 that is movably mated to a support member 86. The body 12can be adjustable in both a horizontal direction and a verticaldirection with respect to the scale 88. A person having ordinary skillin the art will appreciate that a variety of mating techniques can beutilized for removably mating the body 12 to the scale 88. By way ofnon-limiting example, a clamp, screw assembly, buckle, snap, or similarattachment device can be used to mate the body 12 to the scale 88. Theback surface 28 of the body 12 can also optionally or alternativelyinclude a handle (not shown) for grasping and manipulating the device10. A person having ordinary skill in the art will appreciate that thehandle can have any shape or configuration, and should be adapted tofacilitate gripping of the device 10.

Referring back to FIGS. 1 and 2, the device 10 includes a viewingelement 14 mated to, or integrally formed with, the body 12, andpreferably positioned on the front surface 26 at or near the proximalend 22 of the body 12. The viewing element 14 can have a variety ofconfigurations, but preferably extends outward from the front surface 26of the body 12, and includes a bore 30 extending therethrough. The bore30 extends from a proximal end 32 to a distal end 34 of the viewingelement 14, and defines a field of vision F (FIG. 2) that can be viewedby a person looking through the bore 30 in the viewing element 14. Theviewing element 14 can optionally include a lens (not shown) disposedwithin the bore 30 for viewing and optionally for magnifying objectsviewed through the bore 30. The shape and size of the bore 30 can vary,but preferably the bore 30 has a diameter d_(v) and length l_(v) that issufficient to define a field of vision F within which the components 16,18, 20 of the device 10 and the object X can be viewed. In an exemplaryembodiment, the bore 30 has a diameter d_(v) in the range of about 3 to20 mm, and a length l_(v) in the range of about 1 to 100 mm. A personhaving ordinary skill in the art will appreciate that the viewingelement 14 can have a variety of configurations, and a variety ofdifferent types of viewing elements can be utilized with the presentinvention. For example, the viewing element can be formed from a scopeor similar type of device.

The device 10 further includes a reference point indicator 16 that canbe viewed through the viewing element 14, and that is effective toprovide a reference point P which can be used to reference a particularreference point of an object X positioned at a distance from the device10. The reference point indicator 16 is preferably formed from a rigidmember, such as a pin or screw, that extends outward from the frontsurface 26 of the body 12 and forms a substantially sharp referencepoint P. The reference point indicator 16 is preferably positioned at ornear the distal end 24 of the body 12, and within the field of vision Fdefined by the viewing element 14. In use, the reference point indicator16 and the viewing element 14 define a horizontal line of sight S, whichis used to align the device 10 horizontally with respect to an object Xviewed through the viewing element 14 and positioned at a distance fromthe device 10.

A person having ordinary skill in the art will appreciate that thereference point indicator 16 can have a variety of configurations. Byway of non-limiting example, the reference point indicator can include acylindrical o-shaped member, rather than a sharp pointed tip P.Alternatively, the reference point indicator can be formed integrallywith the viewing element 14. For example, where the viewing element 14includes a lens (not shown) disposed within the bore 30, a marking canbe formed on the lens to provide a reference point P. In use, a personlooking through the viewing element 14 can align the reference point Pon the lens with an object X viewing through the viewing element 14 andpositioned at a distance from the device 10.

The device 10 of the present invention further includes a horizontallevel indicator 18 mated to the body 12 and oriented parallel to theline of sight S established by the viewing element 14 and the referencepoint indicator 16. The horizontal level indicator 18 is effective toindicate the horizontal alignment of the device 10, and in particularthe horizontal alignment of the line of sight S. The horizontal levelindicator 18 can be mated to any portion of the body 12, but ispreferably mated to the front surface 26 of the body 12, and ispreferably positioned between the reference point indicator 16 and theviewing element 14 just below the line of sight S. In an exemplaryembodiment, the horizontal level indicator 18 is disposed outside of thefield of vision F, and thus cannot be viewed through the viewing element14.

Horizontal level devices are well known in the art, and a variety ofdifferent devices can be used to indicate the horizontal level of thedevice 10 of the present invention. The most common type of horizontallevel indicator, shown in FIG. 1, is a liquid-filled tube that has asmall air bubble 36 trapped therein. Because liquids always seek theirown level, the bubble 36 will be centered in the tube, as indicated bythe markings 38, when the tube is held level. A person having ordinaryskill in the art will appreciate that virtually any type of horizontallevel indicator device can be used with the device 10 of the presentinvention.

The device 10 can also optionally include a reflector element 20 forfacilitating viewing of the horizontal level indicator 18, particularlywhen the level indicator 18 is positioned outside of the field of visionF. The reflector element 20 includes a reflective surface 40, and isdisposed adjacent the horizontal level indicator 18 and within the fieldof vision F. In the embodiment shown in FIGS. 1-3, the reflector element20 is disposed on the front surface 26 of the body 12 between thereference point indicator 16 and the viewing element 14, and just abovethe line of sight S. The reflective surface 40 is preferably disposed atan angle with A with respect to the horizontal level indicator 18 andthe viewing element 14, such that the horizontal level indicator 18 isvisible through the viewing element 14 via the reflector element 20, asshown in FIG. 3. In an exemplary embodiment, the angle A is betweenabout 25° and 75°, and more preferably is about 45°. The size, surfacecurvature, and shape of the reflector element 20 can also vary, but thereflector element 20 should have a size sufficient to provide areflection of the markings 38 on the horizontal level indicator 18, andthe space between the markings 38. In use, as shown in FIG. 3, thereflector element 20 can be viewed through the viewing element 14, andis effective to provide a reflected image of the markings 38′ on thehorizontal level indicator 18, as well as the air bubble 36′ whenpositioned between the markings 38′.

A person having ordinary skill in the art will appreciate that, whileFIGS. 1-2 illustrate one embodiment of a leveling device 10, the device10 can have a variety of configurations, shapes, and sizes. For example,the horizontal level indicator can be positioned virtually anywhere onthe body 12, or alternatively can be mated to a separate device, such asan external drainage system, for use with the leveling device 10.Moreover, the device 10 can be directly mated to some object other thana body 12. For example, the components 14, 16, 18, 20 can be directlymated to an external drainage system, and in particular to a scale on anexternal drainage system, thereby eliminating the need for a body 12altogether.

In use, the device 10 is effective to indicate the horizontal alignmentof the body 12 with respect to a particular reference point X viewedthrough the viewing element 14 and indicated by the reference point P onthe reference point indicator 16. As shown in FIG. 3, a person lookingthrough the bore 30 in the viewing element 14 can see the referencepoint indicator 16, as well as the reflected image of the horizontallevel indicator 18 in the reflector element 20. The reference pointindicator 16 is used to align the reference point P with an object Xpositioned at a distance apart from the device 10. Simultaneously, thehorizontal level indicator 18 is adjusted until the air bubble 36 ispositioned between the markings 38 on the horizontal level indicator 18,as shown in the reflected image. The horizontal alignment of the body 12with respect to a particular reference point X is thus determined.

In an exemplary embodiment, shown in FIGS. 4 and 5, the device 10 of thepresent invention is used to determine the zero pressure point 92 of anexternal drainage system 80. FIG. 5 illustrates a typical externaldrainage system 80 having a support member 86, a scale 88 mated to orformed on the support member 86, a drip chamber 82 for collecting CSFdrainage, and a collection bag 84 for receiving fluid from the dripchamber 82. In an exemplary embodiment, the scale 88 is slidably movablealong the axis of the support member 86. The collection bag 84 ispreferably fixed to the support member 86, while the drip chamber 82 isslidably movable in a vertical direction with respect to the scale 88. Aperson having ordinary skill in the art will appreciate that the medicaldrainage system 80 can have a variety of configurations.

Referring the FIG. 4, the leveling device 10 is removably attached tothe scale 88 such that the line of sight S, defined by the viewingelement 14 and the reference point indicator 16, is aligned with thezero mark 92 on the scale. The zero pressure point 92 can be determinedby viewing the reference point indicator 16 and the horizontal levelindicator 18 through the bore 30 in the viewing element 14. Thehorizontal level of the device 10 is adjusted by viewing the reflectionof the markings 38′ on the horizontal level indicator 18 through thereflector element 20, and positioning the bubble 36′ on the horizontallevel indicator 18 between the markings 38′. This can be accomplished byrotating either the scale 88 with respect to the support member 86, oralternatively rotating the leveling device 10 with respect to the scale88. Once the horizontal level is adjusted, the reference point P on thereference point indicator 16 is vertically aligned with the referencepoint on an object X, preferably a patient's external auditory canal,positioned at a distance from the device 10. The alignment is preferablyadjusted by sliding the scale 88, with the leveling device 10 matedthereto, in a vertical direction. Once the device 10 is horizontally andvertically level with respect to the particular reference point ofobject X, the scale 88 is locked or fixed into position, therebyaligning the zero mark 92 on the scale 88 with the patient's externalauditory canal. As a result, the zero mark 92 on the scale 88 accuratelyreflects the zero pressure point, and thus the ICP, of the externaldrainage system 80 with respect to the patient. The ICP of the externaldrainage system 80 can then be adjusted, as shown in FIG. 5, by movingthe drip chamber 82 to position the top of the drip chamber 94 adjacentthe desired ICP, as indicated by the indicia 96 on the scale.

One of ordinary skill in the art will appreciate further features andadvantages of the invention based on the above-described embodiments.Accordingly, the invention is not to be limited by what has beenparticularly shown and described, except as indicated by the appendedclaims. All publications and references cited herein are expresslyincorporated herein by reference in their entirety.

1. A method for indicating a horizontal alignment of a body with respectto a target, comprising: viewing a reference point indicator, ahorizontal level indicator, and a target through a viewing element of aleveling device; and vertically aligning the leveling device with thetarget using the reference point indicator while simultaneously aligningthe leveling device horizontally using the horizontal level indicator;wherein the leveling device is coupled to an external drainage systemand is effective to determine a zero-pressure point of the externaldrainage system.
 2. The method of claim 1, wherein the horizontal levelindicator is viewed through the viewing element on a reflector element.3. The method of claim 1, wherein the leveling device is horizontallyaligned by moving a bubble between two markings on the horizontal levelindicator.
 4. The method of claim 1, wherein vertically aligning theleveling device comprises sliding the leveling device relative to avertical support on which the leveling device is mounted.